Or just punt, and use iBGP....

Can't quite do that - you need an IGP to carry the backbone links & the loopbacks - i.e.: just enough so that the iBGP mesh will come up. --asp

On Tue, Jan 05, 1999 at 09:13:18PM -0600, Sean Donelan wrote:

randy@psg.COM (Randy Bush) writes:

...

...

Most of the large ISPs in the US run IS-IS as their IP IGP. In europe a number of PTTs have chosen IS-IS as the IGP for their new IP Internet backbones. That might be an indication if IS-IS is dead.

hypothesis: big isps talk less. except a few loudmouths <g>, and when jhawk gets pissed off <g^2>.

I know why most of the older large ISPs use IS-IS, because it was the only option that worked at the time. But now that some router vendors have come out with workable OSPF implementations, I've been wondering which road the new ISP competitors would take. So far, they've been hiring all the engineering staff away from the older ISPs. And then the engineers set up the new network with the same skills, meaning IS-IS.

But what if you started from a clean slate...

I know of one new network planned by people originally most familiar with OSPF that is now running IS-IS. It did start out as OSPF allright, but when you go beyond 200+ routers in area 0 within 6 months (and still growing) you start wondering whether you shouldn't take a different approach -- and thats when IS-IS comes in handy.

If you didn't have an installed base, and didn't already know one or the other, which would you choose? Or just punt, and use iBGP....

I guess it depends on how large you plan to get :-) - and yes, I know, that OSPF scales quite well if you design it carefully WRT areas, but so does IS-IS... Another way to look at it would be that you could keep on making sloppy networkdesign far longer in an IS-IS network than you could with OSPF ;)

-- Sean Donelan, Data Research Associates, Inc, St. Louis, MO Affiliation given for identification not representation

/Niels Chr. -- Niels Christian Bank-Pedersen, NCB1-RIPE. Network Manager, Tele Danmark NET, IP-section. # rsh -l God universe.all find / -name '*windows*' -exec rm -rf {} \\;